Larger than Belgium or Switzerland, the 52800 square kilometre Central Kalahari Game Reserve, which was set up in 1961, is the largest game reserve in the world. Situated right in the very centre of Botswana, this reserve is characterised by vast open plains, salt pans and ancient riverbeds. Varying from sand dunes with many species of trees and scrubs in the north, to flat bushveld in the central area, the reserve is more heavily wooded in the south, with mopane forests to the south and east. Rainfall is sparse and sporadic and can vary from 170 to 700 millimetres per year. Game viewing for animals which include giraffe, brown hyaena, warthog, wild dog, cheetah, leopard, lion, blue wildebeest, eland, gemsbok, kudu, red hartebeest and springbok, is best between December and April, when the animals tend to congregate in the pans and valleys.